Changeset d50f3e5 in mainline for uspace/lib/posix/src/pthread/keys.c

Timestamp:

2025-03-09T20:06:24Z (16 hours ago)

Author:

Matěj Volf <git@…>

Children:

53e652d

Parents:

af28af6

git-author:

Matěj Volf <git@…> (2025-03-09 20:05:51)

git-committer:

Matěj Volf <git@…> (2025-03-09 20:06:24)

Message:

decrease scrope of pthread keys support

File:

• uspace/lib/posix/src/pthread/keys.c (modified) (6 diffs)

uspace/lib/posix/src/pthread/keys.c

@@ -40 +40 @@
 #include "../internal/common.h"
 
-#define DPRINTF(format, ...) ((void) 0)
+#include <stdio.h>
+#define DPRINTF(format, ...) printf("pthread_keys: " format, ##__VA_ARGS__)
 
 static fibril_local bool fibril_initialized = false;
@@ -51 +52 @@
  */
 #define PTHREAD_KEYS_MAX 100
-static void (*destructors[PTHREAD_KEYS_MAX])(void *);
 
 static fibril_local void *key_data[PTHREAD_KEYS_MAX];
@@ -58 +58 @@
 {
         // initialization is done in setspecific -> if not initialized, nothing was set yet
-        if (!fibril_initialized)
+        if (!fibril_initialized) {
+                DPRINTF("pthread_getspecific(%d) = NULL (uninitialized)\n", key);
                 return NULL;
+        }
 
         assert(key < PTHREAD_KEYS_MAX);
@@ -65 +67 @@
         assert(key > 0);
 
+        DPRINTF("pthread_getspecific(%d) = %p\n", key, key_data[key]);
         return key_data[key];
-}
-
-static void pthread_key_on_fibril_exit(void)
-{
-        if (!fibril_initialized)
-                return;
-
-        for (unsigned i = 0; i < PTHREAD_KEYS_MAX; i++) {
-                /*
-                 * Note that this doesn't cause a race with pthread_key_create:
-                 * if key `i` has not been assigned yet (it could be just being
-                 * created), key_data[i] has never been assigned, therefore it
-                 * is NULL, and the destructor is not checked at all.
-                 */
-                if (key_data[i] != NULL && destructors[i] != NULL)
-                        destructors[i](key_data[i]);
-        }
 }
 
 int pthread_setspecific(pthread_key_t key, const void *data)
 {
+        DPRINTF("pthread_setspecific(%d, %p)\n", key, data);
         if (!fibril_initialized) {
                 DPRINTF("initializing pthread keys\n");
-                errno_t res = fibril_add_exit_hook(pthread_key_on_fibril_exit);
-                if (res != EOK)
-                        return res;
-
                 for (unsigned i = 0; i < PTHREAD_KEYS_MAX; i++) {
                         key_data[i] = NULL;
@@ -108 +91 @@
 int pthread_key_delete(pthread_key_t key)
 {
-        /*
-         * FIXME: this can cause a data race if another fibrill concurrently
-         * runs on_fibril_exit. The obvious solution is to add a rwlock on
-         * the destructors array, which will be needed anyway if we want to
-         * support unlimited number of keys.
-         */
-        destructors[key] = NULL;
-        key_data[key] = NULL;
-
-        // TODO: the key could also be reused
+        // see https://github.com/HelenOS/helenos/pull/245#issuecomment-2706795848
+        not_implemented();
         return EOK;
 }
@@ -124 +99 @@
 {
         unsigned short k = atomic_fetch_add(&next_key, 1);
+        DPRINTF("pthread_key_create(%p, %p) = %d\n", key, destructor, k);
         if (k >= PTHREAD_KEYS_MAX) {
                 atomic_store(&next_key, PTHREAD_KEYS_MAX + 1);
                 return ELIMIT;
         }
+        if (destructor != NULL) {
+                static int __counter = 0;
+                if (__counter == 0) {
+                        fprintf(stderr, "pthread_key_create: destructors not supported\n");
+                }
+                __counter++;
+        }
 
-        destructors[k] = destructor;
         *key = k;
         return EOK;